1. Field of the Invention
This invention relates generally to crimping and swaging operations such as may be applied to ferrules for use in fluid power hose connections, on steel cables, or the like. More particularly the present invention relates to validation of the crimp or swaging process by using crimp or swage force monitoring apparatus, systems and methods, and specifically to automatic control systems and methods for the detection of defective crimps during crimping or swaging processes.
2. Description of the Prior Art
Hydraulic crimpers or swagers are used to assemble hydraulic couplings (fittings) to hose. Such fittings, which are typically post assembled to an end of a finished hose product, typically have a male-stem portion that is insertable into a hose end and a ferrule that is concentric with the male-stem. Together, the male-stem and ferrule define an annular cavity for receiving a hose end. An insert, such as disclosed U.S. Pat. No. 5,267,758 and/or in U.S. patent application Ser. Nos. 12/313,400 and 12/313,406, filed Nov. 20, 2008, each of which are incorporated herein by reference, may be fitted between the ferrule and the hose. The fitting is retained by pinching the hose end in the annular cavity between the ferrule and stem such as by radially reducing some part or element of the ferrule, using a crimping or swaging process. Crimping radially reduces the size of the ferrule by crushing it to a smaller diameter, using a plurality of circumjacently arranged die fingers. Swaging radially reduces the size of the ferrule by forcing it through a (tapered) set of dies. Both crimpers and swagers are typically hydraulically powered/operated. Similarly, crimping or swaging operations may be used in other operations, such as for crimping or swaging ferrules to steel cables for forming a loop in such a cable or to splice two cables together.
Currently there are no crimpers or swagers that can detect defective assemblies during the crimp swage cycle. Failure of defectively crimped or swaged products can be catastrophic in nature. Such defects are typically caused by crimping or swaging failure modes such as the hose not being fully inserted onto the stem and/or into the ferrule prior to crimping, and/or no serrations in the ferrule or on an insert disposed in the ferrule, or by incorrect hose dimensions, or by incorrect crimper diameter settings.
Typical existing methods for detecting such failure modes employ off line processes such as pressure testing of completed final assemblies during post production checks to a predetermined proof pressure, tension load testing to a predetermined proof load or x-raying of crimped product to ensure full insertion and proper position of components. All of these processes are very costly, are not necessarily sensitive enough to capture defective crimping, and typically add additional steps and cost to product production. For example, “offline” pressure testing equipment is very expensive, has slow cycle times, requires additional labor, and its use adds significantly to production times.
Another existing method for detecting potentially defective crimps is employed by Uniflex Hydraulik GmbH. These crimpers check the hydraulic pressure during or at the completion of every crimp cycle. A range of final crimp pressures is set for each crimp, so if the crimp falls outside the final pressure range, the crimp is considered out of specification.